Remy is the combings of people's hair. Often harvested by people picking over rubbish dumps in India. It used to be a cottage industry in Italy at one time.
The hair is hackled out, then dipped in a chemical that dissolves the cuticle of the hair. This means there is no need for it to be root point correct, as hackled out hair cannot possibly be.
Generally it is then coated in silicon, to make the hair appear silky.
As there is no cuticle, this hair is not great for ext as it tends to shed a lot more than cuticle correct hair.